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Walter Roberson


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47,640 total contributions since 2011

I do not do free private consulting. If you want to bring my attention to something, send a link to the MATLAB Answers location.

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Answered
Array indices: using function handles and fminsearch
vec is a cell array. vec(expression) asks to index the cell array at the expression. But the expression is a floating point numb...

4 hours ago | 0

Answered
How to read rows until I find blank row in csv file and copy to another cell?
d = readmatrix(filename) mask = a(isnan(d), 2).'; starts = findstr([false, mask], [0,1]); stops = findstr([mask, false], ...

6 hours ago | 0

Answered
Indexing the output of the function nsumk
result32 = result(3,2) row3 = result(3,:)

6 hours ago | 0

Answered
How to use while true loop
while true x = rand(); if x < 0.1; break; end end

9 hours ago | 0

Answered
How to solve this problem? Error using == Quadratic constraints not supported
x*x + y*y == 1 Reduce the number of variables by replacing y with +/- sqrt(1-x^2) . Run twice, once with y being the positive r...

9 hours ago | 0

Answered
Event-based ODE inside a handle class
You need a static method. ode event functions are not expecting the object to be passed. They are, however, expecting t to be pa...

10 hours ago | 0

Answered
matlab "FoldList" (generalized cumfn)
fold() https://www.mathworks.com/help/symbolic/fold.html

10 hours ago | 0

Answered
convert decimal to hex
sprintf('%02x',V)

11 hours ago | 0

Answered
Adding successive cells in a columns
sum(reshape(table2array(YourTable), 16, [])) but having a table object with only one row and 7921 variables is not at all commo...

12 hours ago | 0

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Answered
How to get datetime with the "Epoch" key to millisecond resolution
t1 = datetime(date1,'ConvertFrom','epochtime','Epoch','2020-01-01','Format','dd-MMM-uuuu HH:mm:ss.sss') For datetime objects, t...

12 hours ago | 0

Answered
Multiple left-hand sides must be separated by commas
[dx(i); dy(i); dz(i); t0(i)] = inv(Mat1(i))*Mat2(i); You need to use comma instead of semicolon there. But it is not goin...

1 day ago | 0

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Answered
Error in solving differential of spherical Bessel function. How to solve it?
diff() has two major uses that are very different. When the first parameter to diff() is numeric then the operation is finite...

1 day ago | 0

Answered
How to Save Large Variables
save('filename.mat','FEATURE', '-v7.3')

1 day ago | 0

Answered
Is there a way to include a header comment for a mat file?
Unfortunately v4 and v5 and v7 mat files were not defined to allow for comments. The exception is that the first 128 bytes of v5...

1 day ago | 0

Answered
Is vectorizing this even possible?
I posted the complete vectorization several days ago; . Unfortunately the person deleted the question. syms v v0 c f(v) = (v+c...

1 day ago | 0

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Answered
I can't save a PSAT file
I suspect that you have a file named settings.m that is interfering with the operation of MATLAB. which -all settings You shou...

1 day ago | 0

Answered
Matlab Licence for students
If you purchase a student license from Mathworks directly then the license does not expire, but your Software Maintenance Servic...

2 days ago | 0

Answered
How can I differentiate between powermod(a,b,c) and mod(a^b,c)
104^45 exceeds 2^53, which is the largest number for which double precision is able to distinguish between adjacent integers. 2^...

2 days ago | 0

Answered
Is it possible to use zero padding in the variable names when creating a symbolic array of automatically generated elements.
No, the code checks that what you pass in is a variable name itself, and if not then it deletes all '%d' and tries again to see ...

2 days ago | 0

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Answered
how to add text/number in an image as it is the part of the image?
Computer Vision Toolbox, use the insertText() function. You can specify the position and color and font and font size; it writes...

2 days ago | 0

Answered
matrix creation from a loop
if i know How to create a loop to create them it would be better also for future research. Our long experience is that it would...

2 days ago | 2

Answered
Multiple Simultaneous open .csv file operations
which does do simultaneous writing but locks the files so they are inaccessable to the second instance That tells us that you a...

2 days ago | 0

Answered
How to return double or float values from poly2sym ?
Is it possible to make poly2sym returning double or float values instead integer fractions as shown below ? No. However, you ca...

2 days ago | 0

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Answered
Crop ROI in an image.
uint8(BW).*I should be fine. However, for the selected region (inside the polygon) all the values are equal 1 and I need to ha...

2 days ago | 0

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Answered
How to display multiple histogram with one run
You did not put in hold on

2 days ago | 0

Answered
error using hdf5lib2
https://www.mathworks.com/matlabcentral/answers/158986-matlab-h5read-get-errors There is no /HDFEOS/GRIDS/OMI Column Amount O3...

2 days ago | 0

Answered
Error using Polyfit: The first two inputs must have the same number of elements. The x can have multiple inputs as columns?
The x can have multiple inputs as columns? doc polyfit "If x is not a vector, then polyfit converts it into a column vector x(...

2 days ago | 1

Answered
Datatip not working. Changing location??
You are passing in vectors of x and y coordinates, but datatip is only defined for scalar x and y. In terms of your plot, f is ...

2 days ago | 0

Answered
How to color the area bounded by several circles?
Fx= [x1,fliplr(x2),fliplr(x3)]; Fy = [y1,fliplr(y2),fliplr(y3)]; fill(Fx, Fy); Tested with input values I made up. For your i...

2 days ago | 0

| accepted

Answered
Trying to input a number of files from a matrix
>> subName = ["10", "12"]; size(subName), 1:size(subName) ans = 1 2 ans = 1 size() with a single parameter al...

2 days ago | 0

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